


Butterfly Effect

by ChaoticFairy (Amanda908565)



Category: Katekyou Hitman Reborn!
Genre: Alternate Universe, Byakuran might be a Mist but he still saw Mukuro and went Mine, Definitely some, Families of Choice, Family, Feel-good, Feels, Flame Lore (Katekyou Hitman Reborn!), Flameswap, Fluff, Found Family, Friendship, Gen, Happy Ending, KHR Rare Pair Week 2020: Storm Day, Mist!Byakuran, Out of Character, Sky!Mukuro, let them be happy
Language: English
Status: Completed
Published: 2020-06-21
Updated: 2020-06-21
Packaged: 2021-03-04 03:55:21
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,585
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24843415
Author URL: https://archiveofourown.org/users/Amanda908565/pseuds/ChaoticFairy
Summary: “I never thought...” Byakuran swallowed thickly. “I never thought a Sky would want to Harmonize with me.”Mukuro didn’t ask why. He understood well enough. He hadn’t trusted Byakuran in the beginning since the man was a Mist, and Mist were tricky. Troublesome. Traitors, usually. Then, he understood even more after he started to live with the Gesso Famiglia. Byakuran was not only a Mist, and a strong one at that, but he had times where he lost his connection with this reality. To most, this would seem like a burden.To Mukuro, Byakuran was not a burden.Prompt:June 21: Storm Day - Flameswap AU/Genderbend
Relationships: Joushima Ken & Kakimoto Chikusa & Rokudou Mukuro, Rokudou Mukuro & Byakuran
Comments: 5
Kudos: 41
Collections: KHR Rare Pair Week 2020





	Butterfly Effect

**Author's Note:**

  * In response to a prompt by Anonymous in the [KHR_Rare_Pair_Week_2020](https://archiveofourown.org/collections/KHR_Rare_Pair_Week_2020) collection. 



> **Prompt:**  
>  June 21: Storm Day - Flameswap AU ~~/Genderbend~~
> 
> -
> 
> Butterfly Effect: In chaos theory, the butterfly effect is the sensitive dependence on initial conditions in which a small change in one state of a deterministic nonlinear system can result in large differences in a later state. 
> 
> My 'small change' would be Mukuro having Sky Flames instead of Mist, and Byakuran having Mist instead of Sky. I hope you guys enjoy!

In the beginning, Mukuro hadn't been expecting to Harmonize with Byakuran.

The man was odd. Odder than him, even, and he had been a child experiment. The mark in his eye proved it. The barcode under Chikusa’s. Ken’s ability to imitate wild animals. They were a strange bunch, but Mukuro kept them together. 

Barely.

Chikusa’s calm managed to mellow out the endless energy that Ken had, but Mukuro found himself consistently caught in a tug of war between the two. He loved them, not that he would ever admit it, but sometimes he just wanted to run away.

Sometimes, he did.

* * *

It was during one such times that he had stumbled across Byakuran. Or, rather, Byakuran stumbled into him. The man’s purple eyes were wide, and...amused? Wait, no, they weren’t purple. Were they? The argument could be made, Mukuro decided. Although, they seemed more lavender to him. So light that they looked almost white sometimes. 

He swallowed, the realization hitting him.

This man was a Mist. 

It wasn’t that he didn’t like Mist users, but he tends not to trust them. Estraneo were a Famiglia filled with Mists and it left a bad taste in his mouth. “Can I help you?” He asked, carefully pushing the man away. His eyes scanned the other for any sort of danger. He blinked. His chest was cold. What...?

“You ruined my dessert,” the man all but whined. “I was really looking forward to trying that new flavor. It’s Fluffernutter.” 

“Fluffernutter...?” Mukuro asked, having no idea what to make of this interaction.

“Yeah, you know, peanut butter and marshmallow fluff? The gelato place decided to make it today.” Mukuro blinked again. The man sighed, “but now you’ve gone and ruined it.”

“I’m sorry...?”

“You should be.”

Mukuro has never been so confused in his life, and that includes when he was first kidnapped. He knew that he should just leave; turn around and send out Chikusa to run errands, but he hasn’t left their dingy apartment in almost a week and Ken was looking at him with poorly concealed concern. 

So what if he didn’t like people? He’d like to think that he had a good reason for it.

(“But you’re a _Sky_ ,” Ken told him, as if that single word held all the answers to the world. “You _need people_.” 

Mukuro glared at the blonde, “I don’t _need_ anyone,” he snapped. “What I need is to be left _alone_ and not badgered, Ken. That’s what I need.”

Later that night when Chikusa curled up against his back, and Ken cuddled up to his front, he pointedly ignored Ken’s comment:

“You need _us_.”)

The man pursed his lips. “Aren’t you going to offer to buy me a new one?”

“What?” That was ridiculous! “You bumped into me!” He could feel his Sky Flames flare slightly before he had the opportunity to hide them. Interest flashed in the man’s face, and Mukuro _hated_ it. He didn’t want the attention. He didn’t care what this guy wanted. He just wanted to go home. He wanted to sleep, and maybe not have to worry about who he would need to pickpocket next so that Ken and Chikusa could have dinner.

“Hmm,” the man hummed, “then perhaps I should offer to buy you a new shirt?” Those lavender eyes fell to his camouflage print top. Mukuro watched his nose scrunch up, making the odd tattoo under his eye shift, too. “It seems you're overdue for a style update, anyway.” The man’s eyes flicked back up, and this time settled on top of Mukuro’s head, where he looked _past_ him. What could he -?

“Rude!” Mukuro hissed, taking another step away from the man. He liked his hair, thank you very much. The style kept it out of his face, and Ken found the large clip for him when he found his own hair clips. It was nice, and it certainly gave him a boost of energy once the Sun found out how to channel his Flames into the hairpiece. His nightmares kept him from sleeping, which made him more tired than he usually was. 

The man gave him a toothy grin, but it was sharp. Much sharper than it should be, and Mukuro felt like a cornered rabbit rather than the bird of prey he usually thought himself as. “Here I am, offering my help, and even going as far to _pay_ for it, and you call me rude?” He tutted. Mukuro felt his eye twitch under the white patch he used to cover the mutation. 

“Thanks, but no.” 

That toothy grin never left the man’s face. It made Mukuro’s skin crawl, but he couldn’t tell if it were in a good or bad way. He was leaning more towards bad. “What’s your name, little Sky?”

Mukuro pursed his lips, “Noneya.” 

“Noneya?” The Mist looked amused. 

“Yeah, Noneya Bidness, and if you would _please_ just excuse me -” Mukuro tried to step around the man, but the asshole moved to stand in front of him. He wanted to scream. Maybe he could stab the guy? No, that would bring him too much attention, and his Sky charm only got him so far. 

“Name’s Byakuran Gesso.” Lavender eyes bore into his own. _Gesso..._

(“You’re a Sky, Mukuro. If you walked into any Famiglia, they’d bend over backwards to help you.”)

Mukuro paused, crossing his arms over his chest. It shifted his jacket, and he was glad that he was wearing gloves, or else his nails would be digging into his palms. After a moment of contemplation, he relented. “You said something about a new shirt?” 

Byakuran’s answering grin melted into something soft. It was a stark contrast to the sharpness and power his bared teeth held before. It seemed _happy_. “Come on, I know just the place!”

For all that Mukuro was supposed to be the Boss, he had no control over the situation.

* * *

Byakuran was apparently made of money. He bought Mukuro this shirt and that jacket. Those fancy leather gloves and these new hair clips. 

The man had wanted to get Mukuro a haircut, but he firmly refused. He liked his hair. He was asked about the dirty clip that was missing a few teeth, and ended up talking about Ken. When he looked too long at a clean, blue knit cap, Byakuran didn’t even ask him if he wanted it, and instead added it to the pile of new clothes he was now lugging around. 

Eventually, his stomach started to make sounds. Byakuran’s eyes lit up at the opportunity, but Mukuro wasn’t sure if this was such a good idea. Ken and Chikusa needed to eat. He could go another day or so. The man seemed to sense his hesitation, and smiled. “How about we drop these off, and you can decide what you want for dinner.” 

Mukuro nodded once, and took a deep breath. He hoped that his two companions were ready for the whirlwind that was Byakuran Gesso.

* * *

“Ken? Chikusa?” He called out, pointedly ignoring Byakuran’s gaze on the back of his head. He knew what it looked like. That’s what it _was_ , unfortunately. They didn’t have identities in the real world. They didn’t have money, except for what they stole. They didn’t have clothes, except for what they were wearing (and now, what was in the bags Mukuro was carrying). They didn’t have a home except for what they made for themselves in this crumbling building that provided only the most basic protection.

All they had were each other. 

“Haaah? Mukuro-sama? You’ve been gone all day!” Ken called out. There was a clatter, and then he could hear someone running. His heart twisted when he realized that Ken’s eyes were red, and so was his nose. 

Had he worried his Sun with his absence? 

Chikusa followed behind him at a more sedate pace. Cool, calm and collected. Mukuro noticed his yo-yos in hand, and he felt his lips curl into a small grin. Leave it to Chikusa to always be on guard. 

Before he could say anything, however, Byakuran peeked out from behind him, chirping, “oh, so _you’re_ the reason he was looking at the hat like that!” He quickly moved in front of Mukuro, putting himself into the direct line of fire, but ignored that in favor of digging around in one of the many bags for the knit hat. 

Mukuro looked at his friends helplessly, and they stared back. He could only imagine what they must be thinking. There was a stranger in what they made their home, and he was so close to Mukuro, and Mukuro was _allowing it_. He had shopping bags filled with clothes, and he was pretty sure that a few strands of hair had come loose from his clip. 

“Mukuro-sama, do we need -” Chikusa started.

“Ah-ha! Here it is!” Byakuran managed to pull free the hat he was looking for, holding it up to his face for inspection before nodding once, and tossing it to Chikusa. “Here you go! It’s lambswool, so it shouldn’t itch too much, and it’ll keep you warm!” Chikusa caught the hat with ease, not looking away from Byakuran. There was some incredulity in his expression, but it was mainly scrutiny. “Anyway, get your stuff together. You can’t stay here. You can stay with the Gesso Famiglia.”

“Eh?” Ken exclaimed. “We don’t even know who you are! Shouldn’t you ask your Boss first?”

Byakuran smiled, and it was sharp teeth once more. Ken bared his in immediate response. “It’s a good thing,” Byakuran started, “that _I’m_ the boss, then, yeah?” 

Mukuro didn’t know how this was his life.

* * *

“We can’t trust him,” Chikusa hissed. 

“Do we really have any other choice?” Mukuro snapped back quietly.

Ken was oddly quiet. There was a pensive look on his face, but then, “...I don’t want to run again, guys.”

Mukuro and Chikusa looked at the blonde, who seemed to be wilting right in front of their eyes. They looked at each other. “Alright,” Mukuro decided. “Alright, we go with Byakuran.”

* * *

Most people at the Gesso Base seemed to give Byakuran a wide berth. It was unusual, Mukuro thought. Usually Bosses were well liked by their underlings, but these ones...they seemed to _fear_ Byakuran. He could practically taste it in the air; on their Flames. A few brave souls looked at him in sympathy, but he ignored them. As strange and as pushy as Byakuran was, the man had been nothing but kind and accommodating to Mukuro and his companions. 

Byakuran had shown them to their rooms. Or, suite rather. It was meant to be for a Sky and his Elements, according to Byakuran. So that they didn’t need to stay apart. It was a sweet gesture, and Ken and Chikusa definitely seemed to appreciate it. 

“You guys want pizza for dinner? I know this cute little shop that has the _best_ pizza. Or maybe you want something else? Panini? Pasta?” Ken’s mouth was watering, and before any of them could respond, Byakuran gave a light laugh. “I’ll just order a bunch of different things. Any allergies?” They shook their heads. “Great! I’m gonna go call in, but please make yourselves at home!”

So, they did.

Ken immediately grabbed the blankets off the bed and began to pile them in the one corner of the room farthest away from the door and any windows. Neither Chikusa or Mukuro stopped him. The blonde looked like he was having the time of his life fluffing up pillows and squishing down the blankets. Mukuro wondered if it was because of whatever the Estraneo Famiglia did to him; the animal instincts that were made a part of him.

Chikusa checked out the entire suite, and even sweeped the room for any bugs that could be planted. He made sure that there were no traps or tricks. Mukuro knew that the other was methodical and thorough, and this was how Chikusa felt of use. 

As for Mukuro? Well, he decided that he was allowed to sit down and think about the day. He wasn’t sure how this happened, or if it were just sheer dumb luck, but he was glad. They were safe.

* * *

Byakuran was a Mist. Mukuro knew that. What he didn’t know, but didn’t come as too much of a surprise was that Byakuran was an _unstable_ Mist. 

Which wouldn’t have been _too_ much of an issue if Byakuran had weaker Mist Flames, but considering how powerful the man was, it was troublesome. 

Mukuro understood why the other famiglia members seemed to fear Byakuran.

He would get this far away look in his eyes, and he’d just start talking. He never said who he was talking to, and Mukuro never asked, but it was plenty unnerving on its own. Byakuran would conjure terrifying illusions, but Mukuro had witnessed worse - had _been_ through worse. 

He found that he was usually the one talking Byakuran out of one of his episodes. Chikusa and Ken would watch, worriedly, but then join him once he deemed it safe. Ken would bring marshmallows and Chikusa would offer one of his (now many) hats. 

They would all sit with Mukuro in their suite, and would try to distract him. They would try to bring him back to their world, and slowly but surely, he would return. 

Mukuro thought it was worth it for the genuine and thankful smile that Byakuran would give them all once he was himself again.

* * *

It wasn’t much of a surprise when they Harmonized. 

Ken and Chikusa let out twin breaths of relief as they felt the new bond settle over them. Mukuro hadn’t even intended for the Harmonization, and yet, here they were. Byakuran looked at him in awe for a few moments before throwing himself at his now Sky. 

“I never thought...” Byakuran swallowed thickly. “I never thought a Sky would want to Harmonize with me.”

Mukuro didn’t ask why. He understood well enough. He hadn’t trusted Byakuran in the beginning since the man was a Mist, and Mist were tricky. Troublesome. Traitors, usually. Then, he understood even more after he started to live with the Gesso Famiglia. Byakuran was not only a Mist, and a strong one at that, but he had times where he lost his connection with this reality. To most, this would seem like a burden. 

To Mukuro, Byakuran was not a burden. 

To Mukuro, Byakuran brought mischief into their lives. He brought happiness and teasing, and too sweet confectioneries. He brought sugar highs, and laughter, and pranks, and support. 

(Byakuran’s face had gone eerily blank once Mukuro explained what happened with the Estraneo Famiglia. The next day, Byakuran had tentatively asked what had become of them, since he could not find any trace. Mukuro had admitted to killing them all, and Byakuran let out a sigh of relief, “good,” he said, “I didn’t want to hear that someone took that opportunity away from you.”)

Mukuro smiled at Byakuran, letting out a laugh. “Welcome to my Island of Misfit Toys, Byakuran.” 

“Oi! What’s that supposed to mean?” Ken shouted from the other side of the room. He eagerly rushed forward, plopping himself on top of his Sky and the new Mist to their group. “Hey, Kaki-pi! Get over here! Puppy pile!”

“No,” Chikusa told him, pushing up the glasses that rested on the bridge of his nose. Mukuro saw how he glanced at Ken, and watched as the Rain’s resolve broke. “Fine. Move over.”

To Mukuro, this felt like home.

**Author's Note:**

> Annnnddd they all lived happily together, supporting each other, and knowing they had each other to fall back on! I know they were probably a tad out of character, but if I'm changing their Flames, and even some of their backstories, they're certainly not going to be the same characters that they are in canon. 
> 
> That said, I do hope you enjoyed the fic! If you did, please remember to hit that kudos button, and if you have the time, comments always make an author's day! (also, I can and will chat with you in the comments lmao)
> 
> Happy khr rare pair week 2020, y'all!


End file.
